1. Field of the Invention
The present invention relates to a display device, and in particular to a multi-domain vertical alignment (MVA) liquid crystal display panel.
2. The Related Arts
Flat display devices, such as liquid crystal display (LCD), possess the advantages of being compact and lightweight, saving energy, and being free of radiation so that the flat display devices gradually replace the traditional cathode ray tube (CRT) displays and become the main stream of display devices. Nowadays, the liquid crystal display devices are widely used in a variety of electronic devices, such as digital televisions, computers, personal digital assistants, mobile phones, and digital cameras.
The currently available liquid crystal display devices are generally twist nematic liquid crystal displays, in-plane switching (IPS) liquid crystal displays, and vertical alignment liquid crystal displays.
FIG. 1 is a schematic view showing a conventional vertical alignment liquid crystal display panel, in which (a) illustrates a schematic view of the vertical alignment liquid crystal display panel in a dark state, and (b) indicates the vertical alignment liquid crystal display panel in a bright state. As shown in FIG. 1, a vertical alignment liquid crystal display panel 100 comprises an upper substrate 110, a lower substrate 120, and a liquid crystal layer 130 interposed between the upper and lower substrates. The upper substrate 110 comprises a glass substrate 111, an electrode layer 112, an alignment film 113, and a polarization plate 114. The lower substrate 120 comprises a glass substrate 121, an electrode layer 122, an alignment film 123, and a polarization plate 124.
Those skilled in the art may appreciate that the upper substrate 110 can be a color filter substrate and further a color filter (not shown) arranged thereon. The electrode layer 112 of the upper substrate 110 is a common electrode layer, which is made of a transparent conductive material (such as ITO or IZO). The lower substrate 120 can be a thin film transistor substrate and further comprises an array of thin film transistors (not shown). The electrode layer 122 of the lower substrate 120 is a pixel electrode layer, which comprises a plurality of pixel electrodes, which is controlled by the corresponding thin film transistors of the thin film transistor array and which are respectively made of a transparent conductive material (such as ITO or IZO). Further, the polarization plate 114 of the upper substrate 110 and the polarization plate 124 of the lower substrate 120 have polarization directions that are substantially perpendicular to each other, namely the polarization directions are different by 90 degrees.
The liquid crystal molecules contained in the liquid crystal layer 130 are negative type liquid crystal molecules, namely having Δε less than 0. Thus, the vertical alignment liquid crystal display panel 110 uses the alignment film 113 of the upper substrate 110 and the alignment film 123 of the lower substrate 120 to have the liquid crystal molecules of the liquid crystal layer 130 substantially perpendicular to the upper substrate 110 and the lower substrate 120 is a dark state.
When no voltage is applied between the electrode layer 112 and the electrode layer 122, the liquid crystal molecules of the liquid crystal layer 130 are not rotated. Since the polarization directions of the polarization plate 114 and the polarization plate 124 are perpendicular to each other, light is not allowed transmit through the vertical alignment liquid crystal display panel 100, which is now set in the dark state, as shown in FIG. 1(a).
When a voltage is applied between the electrode layer 112 and the electrode layer 122, the liquid crystal molecules contained in the liquid crystal layer 130 are rotated, causing rotation of light, so that the light can transmit through the vertical alignment liquid crystal display panel, which is now set in a bright state, as shown in FIG. 1(b).
To avoid the issues of gray level inversion and oblique view angle being excessively small, a technique of division of multiple domain has been developed on the basis of the vertical alignment liquid crystal display panel, which divides a display panel in to a plurality of fields, so as to make the liquid crystal molecules of the liquid crystal layer showing a plurality of tilt directions in order to overcome the above discussed problems.
FIG. 2 is a schematic view showing a conventional multi-domain vertical alignment (MVA) liquid crystal display panel. As shown in FIG. 2, the conventional multi-domain vertical alignment liquid crystal display panel 200 arranges at least one projection 217 on a color filter substrate 210 of the conventional vertical alignment liquid crystal display panel (such as the vertical alignment liquid crystal display panel 100 shown in FIG. 1), and the arrangement of the projection 217 allows nearby liquid crystal molecules to show tilting condition by following the surface contour of the projection 217, whereby the liquid crystal molecules of the liquid crystal layer 230 are lined up in a variety of directions to realize the division of multiple domains.
However, when the conventional multi-domain vertical alignment liquid crystal display panel 200 is in a dark state (namely displaying L0 gray level), the projection 217 also causes the nearby liquid crystal molecules to show corresponding tilting condition and thus light passing through theses liquid crystal molecules are rotated, whereby the rotated light may comprise a component that has a polarization direction corresponding to the polarization plate of the color filter substrates 210. This light component will partly transmit through the multi-domain vertical alignment liquid crystal display panel 200, causing light leakage. Thus, to alleviate the light leakage problem, it is desired to develop a novel liquid crystal display panel.